Implementation of high definition television (HDTV) in the United States is now undergoing testing by the Federal Communications Commission. It is contemplated that such an HDTV system will require additional channel allocations on UHF frequencies which will carry a digital signal. Thus alterations to existing transmitting antennas will be required. The existing TV signal is normally designated an NTSC signal which is analog. It is contemplated that the HDTV digital signal will be located on the same transmission tower. However because the normal NTSC signal is in the VHF frequency range, such VHF antenna cannot simultaneously serve UHF channels. In such cases, the HDTV operation will require separate antenna which may be in a different location of the tower or preferably in a common antenna aperture.
Normally two separate coaxial feed cables would be utilized for each antenna. This is expensive and cumbersome.